Is there a bug with melee attacks suddenly?

I line up multiple attacks on a target but when I trigger them I am face-to-face and the auto attacks are gone and nothing has happened. I am then forced to attack manually.

I am using a super sledge with stun. Could that be the problem? It actually stuns my attack?

Some enemies such as Radscorpion and Mirelurk Hunter can pull you out of V.A.T.S.

Those devils!! And I would add super mutants to that list because that's when I noticed it.

So it's just a thing to be aware of. Thanks!

I sometimes get stuck in place and unable to attack after I do a melee special kill move in vats.